Threaded barrels are not outright illegal in Illinois, but they are heavily regulated. Under the Protect Illinois Communities Act (PICA), which took effect January 10, 2023, a threaded barrel counts as an assault weapon feature on a semiautomatic pistol and also qualifies as a standalone assault weapon attachment. If you owned one before that date, you were required to register it with the Illinois State Police through an endorsement affidavit by January 1, 2024. New acquisition by ordinary civilians is prohibited, and possession without registration is a crime.
How Illinois Regulates Threaded Barrels
The rule lives in 720 ILCS 5/24-1.9 and reaches threaded barrels in two ways.
The first is as a pistol feature. A semiautomatic pistol that accepts a detachable magazine becomes an assault weapon if it also has any one of several features, including a threaded barrel, a second pistol grip, a barrel shroud, a flash suppressor, the ability to accept a magazine outside the pistol grip, or a buffer tube or arm brace designed for shoulder firing. Threaded barrels are not on the equivalent feature list for semiautomatic rifles, which has its own triggers such as pistol grips, folding stocks, and flash suppressors.1Illinois General Assembly. Illinois Compiled Statutes 720 ILCS 5/24-1.9
The second is as a standalone part. Illinois defines an “assault weapon attachment” as any device designed to convert a firearm into one of the listed assault weapons, and the Illinois Administrative Code names a threaded barrel as an example.2Cornell Law School. Illinois Admin Code Title 20, 1230.10 – Definitions The statute also reaches “any part or combination of parts designed or intended to convert a firearm into an assault weapon,” so holding a threaded barrel alongside other components that could assemble into one is independently prohibited.1Illinois General Assembly. Illinois Compiled Statutes 720 ILCS 5/24-1.9
The silencer connection that usually explains threaded-barrel laws elsewhere is largely beside the point here. Silencers are independently illegal to possess in Illinois under 720 ILCS 5/24-1. What matters for the threaded barrel is its classification as an assault weapon feature and attachment, whether or not anyone plans to attach anything to it.
Penalties for Possessing or Selling a Threaded Barrel
PICA’s sentencing cross-references the general weapons penalty provisions in 720 ILCS 5/24-1(b), and the class of offense depends on what you did and whether you have priors.
Possession
A first offense for knowingly possessing an assault weapon (which includes a semiautomatic pistol with a threaded barrel) or a .50 caliber rifle after January 1, 2024, without a valid endorsement affidavit is a Class A misdemeanor. That carries up to 364 days in county jail and fines up to $2,500. A second or subsequent violation involving an assault weapon or .50 caliber rifle becomes a Class 3 felony, punishable by two to five years in prison and fines up to $25,000.1Illinois General Assembly. Illinois Compiled Statutes 720 ILCS 5/24-1.9
Possessing a standalone assault weapon attachment, such as a bare threaded barrel, is a Class A misdemeanor. The statute does not list attachments among the offenses that step up to a felony on a second conviction, so repeated attachment-only possession remains a misdemeanor under the current framework.
Manufacture, Sale, Delivery, Import, or Purchase
Commercial activity is treated more harshly. Manufacturing, selling, delivering, importing, or purchasing an assault weapon or .50 caliber rifle is a Class 3 felony on a first offense, with two to five years in prison and fines up to $25,000. The same conduct involving an attachment (a threaded barrel by itself) or a .50 caliber cartridge is a Class A misdemeanor.1Illinois General Assembly. Illinois Compiled Statutes 720 ILCS 5/24-1.9
Registering Through the Endorsement Affidavit
If you owned a firearm with a threaded barrel, or a standalone threaded barrel, before January 10, 2023, PICA required you to submit an endorsement affidavit through your Firearm Owner’s Identification (FOID) card account by January 1, 2024. That affidavit registers the item with the Illinois State Police.3Illinois State Police. Protect Illinois Communities Act, Regulation on Assault Weapons
You need a valid FOID card first. The application requires an Illinois driver’s license or state ID, a recent photograph, and a $10 fee plus a small processing surcharge for card payments.4Illinois State Police. FOID Frequently Asked Questions The affidavit itself is submitted online through the Illinois State Police Firearms Services Bureau portal at ispfsb.com. There is no separate fee for the endorsement.3Illinois State Police. Protect Illinois Communities Act, Regulation on Assault Weapons
If You Missed the January 1, 2024, Deadline
The Illinois State Police has confirmed that the FOID portal remains open indefinitely for late affidavit submissions, and there are no separate fines or penalties for filing late. That said, possessing an unregistered assault weapon or attachment after the deadline is technically a violation of both the FOID Act and the Criminal Code, and the local jurisdiction could deem a late affidavit invalid or insufficient.3Illinois State Police. Protect Illinois Communities Act, Regulation on Assault Weapons
Practically, filing late is better than not filing at all, but there is exposure for the period between the deadline and acceptance of the affidavit. Whether to accept a late filing rests with local prosecutors and courts, so it is worth speaking with a firearms attorney before submitting one.
Removing the Threaded Barrel From the Classification
If the threaded barrel is the only feature putting a pistol into assault weapon territory, one compliance route is to have the barrel modified so it no longer functions as threaded. This is commonly called pinning and welding: a gunsmith permanently attaches a muzzle device (a thread protector or compensator, for example) so that it cannot be removed without destroying the device or barrel.5ATF. National Firearms Act Handbook
The ATF recognizes several methods as permanent: full-fusion gas or electric steel-seam welding, high-temperature silver soldering at 1,100°F or hotter, and blind pinning with the pin head welded over. Once the device is permanently affixed by one of these methods, the barrel is generally no longer considered threaded for regulatory purposes. For a semiautomatic pistol where the threaded barrel was the only qualifying feature, this can move the firearm out of the assault weapon definition. Use a gunsmith familiar with both federal ATF standards and Illinois law.
Who Is Exempt
PICA carves out categories of people and activities from the assault weapon restrictions, and these exemptions apply to both possession and sale of otherwise-prohibited items:
- Active peace officers as defined in the Criminal Code, plus qualified active and retired law enforcement officers recognized under the federal Law Enforcement Officers Safety Act.
- Federal, state, and local law enforcement agencies equipping their officers.
- Wardens, superintendents, and keepers of prisons and jails.
- Members of the Armed Services, Reserve Forces, or Illinois National Guard on official duty or traveling to and from it.
- Armed security officers at Nuclear Regulatory Commission-regulated facilities who have completed mandated training.
- Contractors licensed under the Private Detective, Private Alarm, Private Security, Fingerprint Vendor, and Locksmith Act of 2004 while performing official duties.
The statute also exempts firearms sanctioned by the International Olympic Committee and USA Shooting for competitive use, and manufacturers and dealers may possess and transfer regulated items for sale to authorized buyers, to the U.S. government, for export, or for sale in other states.1Illinois General Assembly. Illinois Compiled Statutes 720 ILCS 5/24-1.9
One exemption PICA does not include is a general Curio and Relics carve-out. A federal C&R license from the ATF does not by itself exempt you from PICA’s restrictions on assault weapons or attachments. A collectible firearm with a threaded barrel that meets the assault weapon definition still has to be registered through the endorsement affidavit.
Ongoing Constitutional Challenges
PICA has been challenged in court repeatedly since its January 2023 enactment. Illinois courts have generally upheld it so far, but the litigation is not finished, so the obligations described here could shift.
The broader Illinois backdrop is the Illinois Supreme Court’s 2013 decision in People v. Aguilar, which struck down a provision of the aggravated unlawful use of weapons statute that effectively banned carrying loaded firearms outside the home, adopting the reasoning of the Seventh Circuit in Moore v. Madigan. The court also acknowledged that Second Amendment rights are “not unlimited” and remain “subject to meaningful regulation,” language later cited in PICA challenges.6Justia. People v. Aguilar, 2013 IL 112116 After the U.S. Supreme Court’s 2022 decision in New York State Rifle & Pistol Ass’n v. Bruen, which requires firearms regulations to have historical analogues in American tradition, challengers have argued PICA fails that test. Illinois courts have so far rejected those arguments, finding historical support for regulating particularly dangerous weapons. Anyone holding a threaded-barrel firearm in Illinois should track both legislative amendments and court rulings, because either could change what registration and possession require.